/*
 * Copyright (c) 2018-2020 "Graph Foundation,"
 * Graph Foundation, Inc. [https://graphfoundation.org]
 *
 * This file is part of ONgDB.
 *
 * ONgDB is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
/*
 * Copyright (c) 2002-2020 "Neo4j,"
 * Neo4j Sweden AB [http://neo4j.com]
 *
 * This file is part of Neo4j.
 *
 * Neo4j is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
package org.neo4j.helpers.collection;

import java.util.Iterator;

/**
 * Concatenates sub-iterables of an iterable.
 *
 * @see NestingIterator
 *
 * @param <T> the type of items.
 * @param <U> the type of items in the surface item iterator
 */
public abstract class NestingIterable<T, U> implements Iterable<T>
{
    private final Iterable<U> source;

    public NestingIterable( Iterable<U> source )
    {
        this.source = source;
    }

    @Override
    public Iterator<T> iterator()
    {
        return new NestingIterator<T, U>( source.iterator() )
        {
            @Override
            protected Iterator<T> createNestedIterator( U item )
            {
                return NestingIterable.this.createNestedIterator( item );
            }
        };
    }

    protected abstract Iterator<T> createNestedIterator( U item );
}
